JPH03185002A - Film for gasket seal in producing methacrylic resin cast sheet - Google Patents

Abstract

PURPOSE:To obtain a film for gasket seal in producing methacrylic resin cast sheet, consisting of methacrylic resin and vinylidene fluoride resin and having effect capable of preventing leakage of a cast raw material by producing the sheet while winding it on gasket. CONSTITUTION:10-90wt.% methacrylic resin (e.g. methyl methacrylate homopolymer) is blended with 90-10wt.% vinylidene fluoride based resin (e.g. vinylidene fluoride homopolymer) and the blend is fed to bent type twin-screw extruder, where the blend is melted and kneaded at 240 deg.C cylinder temperature and formed into pellet and the pellet is dried and extruded by T-die extrusion method to provide the aimed film having 40mum thickness and 200mm width. Furthermore, the film has high effect capable of preventing leakage of a cast raw material by casting an acrylic resin into sheet while winding the film on a gasket in casting of acrylic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a film for sealing a gasket during methacrylic resin cast board production.

[Conventional technology]

Methacrylic resin cast boards are widely used for lighting equipment, signboards, various building materials, etc. due to their excellent appearance, good weather resistance, mechanical properties, etc.

Methods for producing methacrylic resin cast plates include methyl methacrylate monomers, mixtures of the monomers and partial polymers thereof, or monomer mixtures containing methyl methacrylate as the main component, or mixtures of the monomers and partial polymers thereof. A cell in which a radical polymerization initiator is added to a mixture of and is used as a casting raw material, and the casting raw material is injected between two facing inorganic glass plates or metal plates with a gasket around the periphery and heated. Either by casting method, or by continuously injecting and heating the above-mentioned casting raw material from upstream of a space sealed by gaskets and two stainless steel endless belts with single-sided mirror polishing moving in the same direction at the same speed. One example is the continuous casting method.

[Problem to be solved by the invention]

The gasket used here is generally made of vinyl chloride resin, but methyl methacrylate monomer or methyl methacrylate monomer with a low polymerization rate is used as the casting raw material.
/), when producing a cast plate using a partial polymer or producing a thick cast plate, there is a problem that the casting raw material leaks from the end of the gasket.

[Means to solve the problem]

Therefore, the present inventors conducted extensive research to improve the drawbacks of the conventional manufacturing method described above, and as a result, a film made of a mixed resin containing methacrylic resin and vinylidene fluoride resin in a specific ratio was developed for gaskets. By wrapping it around the periphery and using it as a gasket sealing film, it can be used when making cast plates using methacrylate monomers or low b methyl methacrylate partial polymers as casting raw materials, or when making thick plates. The inventors have discovered that the casting material does not leak from the end of the gasket during the manufacture of cast plates, and that methacrylic resin cast plates can be produced efficiently, and have thus arrived at the present invention.

That is, the gist of the present invention is that methacrylic resin 1
This film is for gasket sealing when making a methacrylic resin cast plate, and is composed of a vinylidene fluoride thread resin of 0 to 90 parts by weight and 90 to 10 parts by weight.

The methacrylic resin constituting the gasket sealing film of the present invention includes alkyl methacrylates in which the alkyl group has 1 to 4 carbon atoms, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc. A homopolymer containing an alkyl acrylate having 1 to 8 atoms, such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, etc., or a predominant amount of at least one of these alkyl methacrylates or alkyl acrylates. Copolymers containing at least one other comonomer copolymerizable with these comonomers as a minor component, or mixtures of these homopolymers and copolymers can be mentioned.

These homopolymers and copolymers are those obtained by various polymerization methods such as suspension polymerization, emulsion polymerization, or bulk polymerization, and homopolymers or copolymers containing methyl methacrylate as a component are preferably used. It will be done. Furthermore, Gaskera)y
- In order to increase the strength of the film alone, a rubber component derived from alkyl acrylate, particularly butyl acrylate, is preferably introduced into the methacrylic resin.

Furthermore, the vinylidene fluoride resin used in the present invention refers to a homopolymer mainly composed of vinylidene fluoride and at least one other polymer copolymerizable with vinylidene fluoride such as tetrafluoroethylene. It means copolymers with monomers and mixtures thereof.

The gasket sealing film of the present invention requires the same components as the component that swells due to the casting raw material and the component that wants to swell, and the content of methacrylic resin in the mixed resin is 10 to 90% by weight.
In particular, when 50 to 70 weight scratches are preferable and the h0 methacrylic resin is less than 10 weight range, when a film made of this mixed resin is wrapped around a gasket and used for cast plate making, the film will not be damaged by the casting raw material. This is not a good case because there is little swelling and the sealing effect of the film is reduced.

In addition, if the methacrylic resin exceeds 90% by weight, the film made of this mixed resin will swell too much and the sealing effect will be reduced even when used in cast plate making, which is preferable. There is no particular limitation on the thickness of the film, but from the viewpoint of the strength of the film itself and ease of handling, it is preferably about 10 to 100 μm.

The method for producing the film for gasket seals of the present invention includes mixing the methacrylic resin and the vinylidene fluoride resin in the above-mentioned specific blending ratio using, for example, a V-type blender, and then using a circular die or a T-die at the tip. It can be obtained by melting, kneading, and molding using a melt extruder.

A stabilizer against heat or light can be added to the gasket sealing film of the present invention, if necessary.

As an example of an embodiment in which the gasket sealing film of the present invention is used, the film is wrapped around one side of a gasket used in casting plate manufacturing, and then used in the same manner as a normal gasket.

This is effective in preventing leakage of the casting material from the end of the gasket, regardless of whether the casting method is performed using the sieve casting method or the continuous casting method.

The effect of preventing the leakage of casting raw materials by the gasket sealing film of the present invention is that the methacrylic resin, which is a constituent component of the gasket sealing film, swells with the casting raw material; This is because the vinylidene chloride resin does not swell as much as the casting raw material, so the swelling of the film prevents the casting raw material from leaking from the end of the gasket while maintaining the strength of the film itself.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Examples 1-4. Comparative Examples 1 to 2 (1) Formation of film A methacrylic resin and a vinylidene fluoride resin were mixed in the proportions shown in Table 1, and this mixture was supplied to a 30 mm diameter vented twin-screw extruder, and the cylinder temperature was The mixture was melt-kneaded at 240°C and shaped into pellets. After drying the resulting beret,
A film having a thickness of 40 μm and a width of 200 μm was obtained by extrusion using a T-die extrusion method.

Table 1 1) Hipet HBB [1OD (Mitsubishi Rayon product)
2) Kynar 721 (Pennwalt Co. product) (2) Production of cast plate Add azobis(2,4-dimethylvaleronitrile) as a polymerization initiator to 100 parts of a partial polymer of methyl methacrylate (viscosity 100 centibois, polymerization rate 104). Part CL06 was melted and used as a casting raw material.

The casting raw material was reduced in pressure to remove dissolved air. This raw material was poured into a cell previously formed to a thickness of 12 cm using two sheets of 650 m x 450 m tempered glass and a vinyl chloride resin gasket wrapped around the film shown in Table 1. Polymerization was carried out in a warm water atmosphere at 82°C for 60 minutes.
The test was carried out for 30 minutes in an air atmosphere at 150°C.

Twenty plates were made under the same conditions, and the sealing performance of the film was judged based on the number of plates from which casting material leaked out of the 20 plates.

The results are shown in Table 2.

Table [Effects of the Invention] The gasket sealing film of the present invention having the composition as described above is highly effective and useful in preventing the leakage of casting raw materials by wrapping it around a gasket when making an acrylic resin cast plate. be.

Claims (1)

[Claims] A film for gasket sealing when making a methacrylic resin cast plate, comprising 10 to 90% by weight of a methacrylic resin and 90 to 10% by weight of a vinylidene fluoride resin.